Re: [Xen-devel] [PATCH 06/10] vpci/header: add teardown cleanup

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jun 20, 2018 at 04:42:30PM +0200, Roger Pau Monne wrote:
> In order to unmap the BARs
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  xen/drivers/vpci/header.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
> index 4363270a55..686e04e35a 100644
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -131,12 +131,15 @@ bool vpci_process_pending(struct vcpu *v)
>          if ( rc == -ERESTART )
>              return true;
>  
> -        spin_lock(&v->vpci.pdev->vpci_lock);
> -        if ( v->vpci.pdev->vpci )
> -            /* Disable memory decoding unconditionally on failure. */
> -            modify_decoding(v->vpci.pdev, !rc && v->vpci.map,
> -                            !rc && v->vpci.rom_only);
> -        spin_unlock(&v->vpci.pdev->vpci_lock);
> +        if ( v->vpci.pdev )
> +        {
> +            spin_lock(&v->vpci.pdev->vpci_lock);
> +            if ( v->vpci.pdev->vpci )
> +                /* Disable memory decoding unconditionally on failure. */
> +                modify_decoding(v->vpci.pdev, !rc && v->vpci.map,
> +                                !rc && v->vpci.rom_only);
> +            spin_unlock(&v->vpci.pdev->vpci_lock);
> +        }
>  
>          rangeset_destroy(v->vpci.mem);
>          v->vpci.mem = NULL;
> @@ -560,7 +563,20 @@ static int init_bars(struct pci_dev *pdev)
>  
>      return (cmd & PCI_COMMAND_MEMORY) ? modify_bars(pdev, true, false) : 0;
>  }
> -REGISTER_VPCI_INIT(init_bars, NULL, VPCI_PRIORITY_MIDDLE);
> +
> +static void teardown_bars(struct pci_dev *pdev)
> +{
> +    uint16_t cmd = pci_conf_read16(pdev->seg, pdev->bus, 
> PCI_SLOT(pdev->devfn),
> +                                   PCI_FUNC(pdev->devfn), PCI_COMMAND);
> +
> +    if ( cmd & PCI_COMMAND_MEMORY )
> +    {
> +        /* Unmap all BARs from guest p2m. */
> +        modify_bars(pdev, false, false);

So modify_bars will eventually call defer_map in most cases (which I
believe are the ones your care about here).

But then the following line sets vpci.pdev to NULL, which means the
check in vpci_process_pending is false and modify_decoding is skipped.
If that what you want?

Wei.

> +        current->vpci.pdev = NULL;


> +    }
> +}
> +REGISTER_VPCI_INIT(init_bars, teardown_bars, VPCI_PRIORITY_MIDDLE);



>  
>  /*
>   * Local variables:
> -- 
> 2.17.1
> 

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